The present invention relates to apparatus for the production of paper envelopes and more particularly to apparatus for the application and drying of latex gum to the seal flaps and body portions of such envelopes.
One type of paper envelope, which may be available in a variety of sizes and configurations, is "self-sealing", i.e., its user-sealable flaps (seal flaps) may be joined by pressure to the body portions of the envelopes. Such envelopes are an alternative to those that are sealed by applying moisture to an adhesive strip on a sealable flap.
The machines for applying and drying the latex gum (latex) are adapted to be compatible in speed of operation with the machines which form the envelopes. Such forming machines die-cut the paper stock to form a blank, fold the cut envelope blank and adhere the required portions to form the envelope.
For example, U.S. Pat. No. 3,915,881, which names Robert Cohn as inventor, entitled "Apparatus For Applying Sealing Material To Envelopes", shows an apparatus for applying latex sealing material (otherwise known as latex gum or latex) to the closure flap (seal flap) and opposite body portion of an envelope. The apparatus utilizes a conveyor belt having a triangular path, a latex applier and a dielectric dryer.